On 2018-01-24 13:25, Ken Brown wrote:
> On 1/20/2018 6:49 PM, Ken Brown wrote:
>> On 1/20/2018 7:23 AM, Ken Brown wrote:
>>> On 1/19/2018 10:27 PM, Ken Brown wrote:
>>>> Here's another issue that's come up with _FORTIFY_SOURCE. One of the
>>>> emacs source files, fileio.c, makes use of a pointer to readlinkat.
>>>> When _FORTIFY_SOURCE > 0, this leads to an "undefined reference to
>>>> `__ssp_protected_readlinkat'" linking error. Does this sound like
>>>> something that will be fixed with the new gcc release?
>>>
>>> I got to this sooner than expected:
>>>
>>> $ cat ssp_test.c
>>> #define _FORTIFY_SOURCE 1
>>> #include <unistd.h>
>>> void foo (ssize_t (*preadlinkat) (int, char const *, char *, size_t));
>>>
>>> void baz ()
>>> {
>>> foo (readlinkat);
>>> }
>
> The following patch seems to fix the problem:
>
> -#define __ssp_inline extern __inline__ __attribute__((__always_inline__,
> __gnu_inline__))
> +#define __ssp_inline extern __inline__ __attribute__((__always_inline__))No, that would have other consequences: https://gcc.gnu.org/onlinedocs/gcc/Inline.html > I arrived at this by comparing Cygwin's ssp.h with NetBSD's, on which > Cygwin's was based, and I noticed that NetBSD didn't use __gnu_inline__. The BSDs also stuck with GCC 4.2 due to licensing reasons, so you can't always compare. > Yaakov, is there a reason that Cygwin needs __gnu_inline__? Because the semantics of inline changed in GCC 4.3. > It apparently prevents fortified functions from being used as function > pointers. I am currently testing the following, which seems to match glibc in this detail: --- a/newlib/libc/include/ssp/ssp.h +++ b/newlib/libc/include/ssp/ssp.h @@ -51,7 +51,6 @@ __chk_fail() #define __ssp_decl(rtype, fun, args) \ rtype __ssp_real_(fun) args __asm__(__ASMNAME(#fun)); \ -__ssp_inline rtype fun args __asm__(__ASMNAME("__ssp_protected_" #fun)); \ __ssp_inline rtype fun args #define __ssp_redirect_raw(rtype, fun, args, call, cond, bos) \ __ssp_decl(rtype, fun, args) \ -- Yaakov
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